Display device and method of manufacturing the same

ABSTRACT

A display device and a method of manufacturing the same are provided. A display device includes: a plastic substrate including: a display portion including organic light emitting diodes, and a pad portion including chip-on-films, a lower protective member attached to an entire lower surface of the plastic substrate, and an upper protective member attached to an upper surface of the plastic substrate, the upper protective member covering at least the display portion and both edges of the pad portion.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority of Korean Application No.10-2016-0138426, filed on Oct. 24, 2016, the entirety of which is herebyincorporated by reference.

BACKGROUND 1. Technical Field

The present disclosure relates to a display device, and, moreparticularly, to display device for preventing damage of a plasticsubstrate, and a method of manufacturing the same.

2. Discussion of the Related Art

With the development of an information society, demands for displaydevices displaying an image are increasing in various ways. In the fieldof the display devices, a large-sized cathode ray tube (CRT) display hasbeen rapidly replaced by a flat panel display (FPD) having advantages ofa thin profile, light weight, and a large-sized screen. Examples of theflat panel display include a liquid crystal display (LCD), a plasmadisplay panel (PDP), an organic light-emitting diode (OLED) display, andan electrophoresis display (EPD).

An OLED display includes self-emitting elements capable of emittinglight by themselves, and has advantages of a fast response time, a highemission efficiency, a high luminance, and a wide viewing angle. Inparticular, the OLED display can be manufactured on a flexible plasticsubstrate. The OLED display has additional advantages of a lower drivingvoltage, lower power consumption, and better color tone as compared to aplasma display panel or an inorganic electroluminescent display.

In an OLED display manufactured on a flexible plastic substrate,polyimide is coated on a glass substrate; elements, such as an organiclight-emitting diode including a thin film transistor, an organic layer,etc. are manufactured; and a flexible printed circuit board, such as achip-on-film (COF), is attached to a pad portion. A process forseparating the glass substrate is performed, and then protective filmsare attached to an upper part and a lower part of a panel, therebymanufacturing the OLED display including a flexible polyimide substrate.

FIGS. 1 and 2 are cross-sectional views of an OLED display according toa related art. FIG. 3 is an image illustrating a damaged pad portion ina related art.

With reference to FIGS. 1 and 2, an OLED display according to a relatedart is configured such that an upper protective film UP and a lowerprotective film LP are respectively attached to a front surface and aback surface of a plastic substrate PI on which elements, such as anorganic light-emitting diode, are formed, a chip-on-film COF is attachedto a pad portion PD positioned on one side of the plastic substrate PI,and a resin layer RE is coated on the pad portion PD to protect the padportion PD. However, because the pad portion PD or an edge of theplastic substrate PI is exposed to the outside of the upper and lowerprotective films UP and LP, there is a problem that the plasticsubstrate PI is easily torn out by an external impact. For example, asshown in FIG. 3, the pad portion PD was entirely torn out, as shown bythe string of chip-on-film elements. Thus, there are problems that theOLED display is damaged by a damage of the plastic substrate PI, and adefective driving of the OLED display occurs.

SUMMARY

Accordingly, the present disclosure is directed to a display device anda method of manufacturing the same that substantially obviate one ormore of the issues due to limitations and disadvantages of the relatedart.

An aspect is to provide a display device capable of preventing asubstrate from being damaged by an external impact.

Another aspect is to provide a display device capable of preventing adamage and a defective driving of the display device.

Additional features and aspects will be set forth in the descriptionthat follows, and in part will be apparent from the description, or maybe learned by practice of the inventive concepts provided herein. Otherfeatures and aspects of the inventive concepts may be realized andattained by the structure particularly pointed out in the writtendescription, or derivable therefrom, and the claims hereof as well asthe appended drawings.

To achieve these and other aspects of the inventive concepts as embodiedand broadly described, there is provided a display device, including: aplastic substrate including: a display portion including organic lightemitting diodes, and a pad portion including chip-on-films, a lowerprotective member attached to an entire lower surface of the plasticsubstrate, and an upper protective member attached to an upper surfaceof the plastic substrate, the upper protective member covering at leastthe display portion and both edges of the pad portion.

In another aspect, there is provided a method of manufacturing a displaydevice, including: providing a plastic substrate including: providing adisplay portion including organic light emitting diodes, providing a padportion, attaching chip-on-films to the pad portion, attaching a lowerprotective member to an entire lower surface of the plastic substrate,and attaching an upper protective member to an upper surface of theplastic substrate, the upper protective member covering at least thedisplay portion and both edges of the pad portion.

Other systems, methods, features and advantages will be, or will become,apparent to one with skill in the art upon examination of the followingfigures and detailed description. It is intended that all suchadditional systems, methods, features and advantages be included withinthis description, be within the scope of the present disclosure, and beprotected by the following claims. Nothing in this section should betaken as a limitation on those claims. Further aspects and advantagesare discussed below in conjunction with the embodiments of thedisclosure. It is to be understood that both the foregoing generaldescription and the following detailed description of the presentdisclosure are examples and explanatory, and are intended to providefurther explanation of the disclosure as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, that may be included to provide a furtherunderstanding of the disclosure and are incorporated in and constitute apart of this specification, illustrate embodiments of the disclosure andtogether with the description serve to explain various principles of thedisclosure.

FIGS. 1 and 2 are cross-sectional views of an organic light-emittingdiode (OLED) display according to a related art.

FIG. 3 is an image illustrating a damaged pad portion in a related art.

FIG. 4 is a schematic block diagram of an organic light-emitting diode(OLED) display according to an example embodiment.

FIG. 5 illustrates a first example of a circuit configuration of asubpixel;

FIG. 6 illustrates a second example of a circuit configuration of asubpixel.

FIG. 7 is a plan view of an OLED display according to a first exampleembodiment.

FIG. 8 is a cross-sectional view illustrating a subpixel of an OLEDdisplay according to a first example embodiment.

FIG. 9 is a cross-sectional view taken along line I-I′ of FIG. 7.

FIG. 10 is a cross-sectional view taken along line II-II′ of FIG. 7.

FIG. 11 is a plan view of an OLED display according to a first exampleembodiment.

FIG. 12 is a plan view of a display device according to a second exampleembodiment.

FIG. 13 is a cross-sectional view taken along line III-III′ of FIG. 12.

FIG. 14 is a cross-sectional view taken along line IV-IV′ of FIG. 12.

FIG. 15 is a plan view of a display device according to a second exampleembodiment.

FIG. 16 is an image illustrating a display device according to anexample embodiment used in an experiment.

FIG. 17 is an image illustrating an experiment when an impact is appliedto a display device according to an example embodiment.

FIG. 18 is an image illustrating an experiment after an impact isapplied to a display device according to an example embodiment.

Throughout the drawings and the detailed description, unless otherwisedescribed, the same drawing reference numerals should be understood torefer to the same elements, features, and structures. The relative sizeand depiction of these elements may be exaggerated for clarity,illustration, and convenience.

DETAILED DESCRIPTION

Reference will now be made in detail to some embodiments of the presentdisclosure, examples of that may be illustrated in the accompanyingdrawings. In the following description, when a detailed description ofwell-known functions or configurations related to this document isdetermined to unnecessarily cloud a gist of the inventive concept, thedetailed description thereof will be omitted. The progression ofprocessing steps and/or operations described is an example; however, thesequence of steps and/or operations is not limited to that set forthherein and may be changed as is known in the art, with the exception ofsteps and/or operations necessarily occurring in a particular order.Like reference numerals designate like elements throughout. Names of therespective elements used in the following explanations are selected onlyfor convenience of writing the specification and may be thus differentfrom those used in actual products.

In the description of embodiments, when a structure is described asbeing positioned “on or above” or “under or below” another structure,this description should be construed as including a case in which thestructures contact each other as well as a case in which a thirdstructure is disposed therebetween.

Example embodiments are described below with reference to FIGS. 4 to 18.

FIG. 4 is a schematic block diagram of an OLED display according to anexample embodiment. FIG. 5 illustrates a first example of a circuitconfiguration of a subpixel. FIG. 6 illustrates a second example of acircuit configuration of a subpixel.

With reference to the FIG. 4 example, an OLED display according to anexample embodiment may include an image processing unit 10, a timingcontroller 20, a data driver 30, a gate driver 40, and a display panel50. The image processing unit 10 may output a data signal DATA and adata enable signal DE supplied from the outside. In addition to the dataenable signal DE, the image processing unit 10 may output one or moreof: a vertical sync signal, a horizontal sync signal, and a clocksignal. For convenience of explanation, these signals are not shown. Theimage processing unit 10 may be formed on a system circuit board as anintegrated circuit (IC).

The timing controller 20 may receive the data signal DATA and drivingsignals, including the data enable signal DE or the vertical syncsignal, the horizontal sync signal, the clock signal, etc. from theimage processing unit 10. Based on the driving signals, the timingcontroller 20 may output a gate timing control signal GDC forcontrolling operation timing of the gate driver 40, and a data timingcontrol signal DDC for controlling operation timing of the data driver30. The timing controller 20 may be formed on a control circuit board asan IC.

The data driver 30 may sample and latch the data signal DATA receivedfrom the timing controller 20 in response to the data timing controlsignal DDC supplied from the timing controller 20, and may convert thesampled and latched data signal DATA using gamma reference voltages. Thedata driver 30 may output the converted data signal DATA to data linesDL1 to DLn. The data driver 30 may be attached to a substrate as an IC.

The gate driver 40 may output a gate signal while shifting a level of agate voltage in response to the gate timing control signal GDC suppliedfrom the timing controller 20. The gate driver 40 may output the gatesignal to gate lines GL1 to GLm. The gate driver 40 may be formed on agate circuit board as an IC, or may be formed on the display panel 50 ina gate-in-panel (GIP) manner.

The display panel 50 may display an image in response to the data signalDATA and the gate signal respectively received from the data driver 30and the gate driver 40. The display panel 50 may include subpixels SPfor displaying an image.

As shown in the FIG. 5 example, each subpixel may include a switchingtransistor SW, a driving transistor DR, a compensation circuit CC, andan organic light-emitting diode (OLED). The OLED may operate to emitlight based on a driving current generated by the driving transistor DR.

The switching transistor SW may perform a switching operation so that adata signal supplied through a first data line DL1 may be stored in acapacitor Cst as a data voltage in response to a gate signal suppliedthrough a gate line GL1. The driving transistor DR may enable a drivingcurrent to flow between a high potential power line VDD and a lowpotential power line GND (not limited to a ground potential) based onthe data voltage stored in the capacitor Cst. The compensation circuitCC is a circuit for compensating for a threshold voltage of the drivingtransistor DR. A capacitor connected to the switching transistor SW orthe driving transistor DR may be mounted inside the compensation circuitCC. The compensation circuit CC may include one or more thin filmtransistors (TFTs) and a capacitor. Configuration of the compensationcircuit CC may be variously changed depending on a compensation method.A brief description of the compensation circuit CC will be made.

As shown in the FIG. 6 example, a subpixel including the compensationcircuit CC may further include a signal line and a power line fordriving a compensation TFT and supplying a predetermined signal orelectric power. The gate line GL1 may include a first gate line GL1 asupplying the gate signal to the switching transistor SW, and a secondgate line GL1 b for driving the compensation TFT included in thesubpixel. The added power line may be defined as an initialization powerline INIT for initializing a predetermined node of the subpixel to apredetermined voltage. However, this is merely an example, andembodiments are not limited thereto.

FIGS. 5 and 6 illustrate that one subpixel may include the compensationcircuit CC by way of example. However, the compensation circuit CC maybe omitted, for example, when an object (e.g., the data driver 30) to becompensated is positioned outside the subpixel. The subpixel may have aconfiguration of 2T(Transistor)1C(Capacitor) in which the switchingtransistor SW, the driving transistor DR, the capacitor, and the OLEDare provided. However, when the compensation circuit CC is added to thesubpixel, the subpixel may have various configurations, such as 3T1C,4T2C, 5T2C, 6T2C, 7T2C, or the like. Also, FIGS. 5 and 6 illustrate thatthe compensation circuit CC may be positioned between the switchingtransistor SW and the driving transistor DR by way of an example.However, the compensation circuit CC may be further positioned betweenthe driving transistor DR and the OLED. The position and the structureof the compensation circuit CC are not limited to the ones illustratedin FIGS. 5 and 6.

First Example Embodiment

FIG. 7 is a plan view of an OLED display according to a first exampleembodiment. FIG. 8 is a cross-sectional view illustrating a subpixel ofan OLED display according to a first example embodiment. FIG. 9 is across-sectional view taken along line I-I′ of FIG. 7. FIG. 10 is across-sectional view taken along line II-II′ of FIG. 7. FIG. 11 is aplan view of an OLED display according to a first example embodiment.

With reference to the FIG. 7 example, an OLED display may include aplastic substrate PI, a display portion A/A, and a pad portion PDdisposed on one side of the plastic substrate PI outside the displayportion A/A. The display portion A/A may include a plurality ofsubpixels SP. For example, R (red), G (green), and B (blue) subpixels orR, G, B, and W (white) subpixels of the display portion A/A may emitlight to represent the full color. Chip-on-films COF may be attached tothe pad portion PD disposed on one side, for example, the lower side ofthe display portion A/A. A data signal and electric power may be appliedto a plurality of signal lines (not shown) connected to the displayportion A/A through the chip-on-films COF. Although not shown, the OLEDdisplay may further include a gate-in-panel (GIP) driver on one side ofthe plastic substrate PI.

A cross-sectional structure of a subpixel SP of the OLED displayaccording to an embodiment is described below with reference to FIG. 8.As shown in the FIG. 8 example, in the OLED display according to anembodiment, a first buffer layer BUF1 may be positioned on the plasticsubstrate PI. The plastic substrate PI may be, for example, a polyimidesubstrate. Thus, the plastic substrate PI according to an embodiment mayhave flexible characteristics. The first buffer layer BUF1 may protect athin film transistor, formed in a subsequent process from impurities,for example, alkali ions that may be discharged from the plasticsubstrate PI. The first buffer layer BUF1 may be, for example, a siliconoxide (SiO_(x)) layer, a silicon nitride (SiN_(x)) layer, or amultilayer thereof.

A shield layer LS may be positioned on the first buffer layer BUF1. Theshield layer LS may prevent a reduction in a panel driving current,which may be generated by using a polyimide substrate. A second bufferlayer BUF2 may be positioned on the shield layer LS. The second bufferlayer BUF2 may protect a thin film transistor, formed in a subsequentprocess, from impurities, for example, alkali ions discharged from theshield layer LS. The second buffer layer BUF2 may be, for example, asilicon oxide (SiO_(x)) layer, a silicon nitride (SiN_(x)) layer, or amultilayer thereof.

A semiconductor layer ACT may be positioned on the second buffer layerBUF2, and may be formed of, e.g., a silicon semiconductor or an oxidesemiconductor. The silicon semiconductor may include, for example,amorphous silicon or crystallized polycrystalline silicon. Thepolycrystalline silicon has a high mobility (for example, more than 100cm²/Vs), low power consumption, and excellent reliability. Thus, thepolycrystalline silicon can be applied for a gate driver and/or amultiplexer (MUX) for use in a driving element or applied to a drivingTFT of each pixel of the OLED display. Because the oxide semiconductorhas a low OFF-current, the oxide semiconductor may be suitable for aswitching TFT which has a short ON-time and a long OFF-time. Further,because the oxide semiconductor may increase a voltage hold time of thepixel due to the low OFF-current, the oxide semiconductor may besuitable for a display device requiring a low-speed drive and/or lowpower consumption. In addition, the semiconductor layer ACT may includea drain region and a source region, each including p-type or n-typeimpurities, and may also include a channel region between the drainregion and the source region.

A gate insulating layer GI may be positioned on the semiconductor layerACT, and may be formed of a silicon oxide (SiO_(x)) layer, a siliconnitride (SiN_(x)) layer, or a multilayer thereof. A gate electrode GAmay be positioned on the gate insulating layer GI at a locationcorresponding to a predetermined region (e.g., the channel region whenimpurities are injected) of the semiconductor layer ACT. The gateelectrode GA may be formed of, for example, one or more of: molybdenum(Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel(Ni), neodymium (Nd), copper (Cu), or a combination thereof. Further,the gate electrode GA may be a multilayer, which may be formed of, forexample, one or more of: molybdenum (Mo), aluminum (Al), chromium (Cr),gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), or acombination thereof. For example, the gate electrode GA may be formed asa double layer, e.g., of Mo/Al—Nd or Mo/Al.

An interlayer dielectric layer ILD may be positioned on the gateelectrode GA, and may insulate the gate electrode GA. The interlayerdielectric layer ILD may be formed, for example, of a silicon oxide(SiO_(x)) layer, a silicon nitride (SiN_(x)) layer, or a multilayerthereof. Contact holes CH exposing a portion of the semiconductor layerACT may be formed where each of the interlayer dielectric layer ILD andthe gate insulating layer GI is formed.

A drain electrode DE and a source electrode SE may be positioned on theinterlayer dielectric layer ILD. The drain electrode DE may be connectedto the semiconductor layer ACT through the contact hole CH exposing thedrain region of the semiconductor layer ACT. The source electrode SE maybe connected to the semiconductor layer ACT through the contact hole CHexposing the source region of the semiconductor layer ACT. Each of thesource electrode SE and the drain electrode DE may be formed as a singlelayer or as a multilayer. When each of the source electrode SE and thedrain electrode DE is formed as the single layer, each of the sourceelectrode SE and the drain electrode DE may be formed, for example, ofone or more of: molybdenum (Mo), aluminum (Al), chromium (Cr), gold(Au), titanium (Ti), nickel (Ni), neodymium (Nd), copper (Cu), or acombination thereof. When each of the source electrode SE and the drainelectrode DE is formed as the multilayer, each of the source electrodeSE and the drain electrode DE may be formed, for example, as a doublelayer of, e.g., Mo/Al—Nd or as a triple layer of, e.g., Ti/Al/Ti,Mo/Al/Mo, or Mo/Al—Nd/Mo. Thus, a thin film transistor TFT including thesemiconductor layer ACT, the gate electrode GA, the source electrode SE,and the drain electrode DE may be formed.

Further, a passivation layer PAS may be positioned on the plasticsubstrate PI including the thin film transistor TFT. The passivationlayer PAS may be an insulating layer protecting the component underlyingthe passivation layer PAS, and may be formed, for example, of a siliconoxide (SiO_(x)) layer, a silicon nitride (SiN_(x)) layer, or amultilayer thereof. A color filter CF may be positioned on thepassivation layer PAS. The color filter CF may convert white lightemitted by an organic light-emitting diode OLED into red, green, or bluelight. An overcoat layer OC may be positioned on the color filter CF.The overcoat layer OC may be a planarization layer for reducing a heightdifference (or step coverage) of an underlying structure, and may beformed, for example, of an organic material, such as polyimide,benzocyclobutene-based resin, and acrylate. For example, the overcoatlayer OC may be formed through a spin-on-glass (SOG) method for coatingthe organic material in a liquid state, and then curing the organicmaterial.

A via hole VIA exposing the drain electrode DE of the thin filmtransistor TFT may be positioned in a portion of the overcoat layer OC.The organic light-emitting diode OLED may be positioned on the overcoatlayer OC. More specifically, a first electrode ANO may be positioned onthe overcoat layer OC. The first electrode ANO may serve as a pixelelectrode, and may be connected to the drain electrode DE of the thinfilm transistor TFT through the via hole VIA. The first electrode ANOmay be an anode, and may be formed, for example, of a transparentconductive material, such as indium tin oxide (ITO), indium zinc oxide(IZO), and/or zinc oxide (ZnO). When the first electrode ANO is areflective electrode, the first electrode ANO may further include areflective layer. The reflective layer may be formed, for example, ofone or more of: aluminum (Al), copper (Cu), silver (Ag), nickel (Ni),palladium (Pd), or a combination thereof. For example, the reflectivelayer may be formed of an Ag/Pd/Cu (APC) alloy.

In addition, a bank layer BNK defining pixels may be positioned on theplastic substrate PI including the first electrode ANO. The bank layerBNK may be formed of an organic material, such as polyimide,benzocyclobutene-based resin, and/or acrylate. The bank layer BNK mayinclude a pixel definition portion OP exposing the first electrode ANO.An organic layer OLE contacting the first electrode ANO may bepositioned at a front surface of the plastic substrate PI. The organiclayer OLE may be a layer in which electrons and holes combine and emitlight. A hole injection layer and/or a hole transport layer may bepositioned between the organic layer OLE and the first electrode ANO. Anelectron injection layer and/or an electron transport layer may bepositioned on the organic layer OLE.

A second electrode CAT may be positioned on the organic layer OLE, andmay be positioned on an entire surface of the display area A/A (see theFIG. 4 example). In addition, the second electrode CAT may be a cathodeelectrode, and may be formed, for example, of one or more of: magnesium(Mg), calcium (Ca), aluminum (Al), silver (Ag), or a combinationthereof, each having a low work function. When the second electrode CATis a transmissive electrode, the second electrode CAT may be thin enoughto transmit light. Further, when the second electrode CAT is areflective electrode, the second electrode CAT may be thick enough toreflect light.

An upper protective member UP may be attached to an upper surface of theplastic substrate PI, on which the thin film transistor TFT and theorganic light-emitting diode OLED may be formed, through an adhesivelayer ADL. The upper protective member UP may be, for example, atransparent plastic substrate or a metal thin film. Further, a lowerprotective member LP may be attached to a lower surface of the plasticsubstrate PI. Because the lower protective member LP may have totransmit light, the lower protective member LP may be formed of atransparent plastic substrate.

With reference to the examples of FIGS. 7 to 9, the lower protectivemember LP may be disposed on the entire lower surface of the plasticsubstrate PI, and the upper protective member UP may be disposed on theupper surface of the plastic substrate PI. Because no component may bepresent on the lower surface of the plastic substrate PI, the lowerprotective member LP may be attached to the entire lower surface of theplastic substrate PI. Further, a resin layer RE may be disposed to coverthe chip-on-films COF on the pad portion PD and the pad portion PD.

The pad portion PD may be positioned on the upper surface of the plasticsubstrate PI. The chip-on-films COF may be attached to the pad portionPD. The upper protective member UP may not be attached to a portion ofthe pad portion PD to which the chip-on-films COF are attached. Thus,the upper protective member UP may be disposed on the entire uppersurface of the plastic substrate PI, except for a portion of the padportion PD.

Because the upper protective member UP and the lower protective memberLP positioned on and below the plastic substrate PI may cover theplastic substrate PI, the plastic substrate PI can be prevented frombeing damaged by an external impact. For example, in the related art,when the side of the plastic substrate PI may be most vulnerable to animpact, and may generate cracks, the impact may be propagated toelements inside the plastic substrate PI, thus causing damage of thedisplay device. Thus, embodiments may cover the plastic substrate PIusing the upper protective member UP and the lower protective member LP,thereby preventing damage of the plastic substrate PI.

As such, all the sides of the lower protective member LP may be formedto coincide with all the sides of the plastic substrate PI. For example,the lower protective member LP and the plastic substrate PI may have thesame size. Hence, the lower protective member LP may be attached to theentire lower surface of the plastic substrate PI, and may cover theentire lower surface of the plastic substrate PI. In addition, the sidesof the upper protective member UP may be formed to coincide with thesides of the plastic substrate PI, except for the side of the plasticsubstrate PI on which the pad portion PD may be formed.

With reference to the examples of FIGS. 7 and 10, in the firstembodiment, the upper protective member UP may be disposed to cover bothedges of the plastic substrate PI, even at the side on which the padportion PD may be formed. As shown in FIG. 7, the plurality ofchip-on-films COF may be attached to the pad portion PD, and edges ofthe plastic substrate PI may be positioned outside the left side and theright side of the pad portion PD, to which the chip-on-film COF may notbe attached. The upper protective member UP may include firstprotrusions PP1 protruding to the pad portion PD. The first protrusionsPP1 may be disposed to overlap the edges of the plastic substrate PI.Thus, the upper protective member UP may be disposed on the entire uppersurface of the plastic substrate PI, except for a portion to which thechip-on-films COF may be attached. The upper protective member UPaccording to the embodiment may be disposed at both edges of the plasticsubstrate PI, even in the area in which the pad portion PD may beformed. Hence, even when the impact is applied to the edges of theplastic substrate PI, the upper protective member UP can prevent theplastic substrate PI from being torn out in the formation area of thepad portion PD.

As shown in the example of FIG. 11, as another example of the firstembodiment, the lower protective member LP may be disposed on the entirelower surface of the plastic substrate PI. The upper protective memberUP may be disposed to cover portions between both edges of the plasticsubstrate PI and the chip-on-films COF in the formation area of the padportion PD.

The upper protective member UP may include first protrusions PP1covering both edges at the side of the plastic substrate PI on which thepad portion PD is disposed, and second protrusions PP2 covering theplastic substrate PI between the chip-on-films COF. For example, thesecond protrusions PP2 may extend and protrude between the chip-on-filmsCOF, and may be disposed to coincide with one side of the plasticsubstrate PI. Accordingly, the upper protective member UP may bedisposed on the entire upper surface of the plastic substrate PI, exceptfor a portion to which the chip-on-films COF may be attached, therebypreventing the plastic substrate PI positioned at the pad portion PDfrom being torn out when the impact is applied to the edge of theplastic substrate PI.

As described above, the display device according to the first embodimentmay form the lower protective member LP on the entire lower surface ofthe plastic substrate PI and forms the upper protective member UP on theentire upper surface of the plastic substrate PI, except for a portionto which the chip-on-films COF may be attached, thereby preventing theplastic substrate PI from being damaged by the impact applied to theside of the plastic substrate PI. Thus, the first embodiment can preventthe damage and defective driving of the display device.

Second Example Embodiment

FIG. 12 is a plan view of a display device according to a second exampleembodiment. FIG. 13 is a cross-sectional view taken along line III-III′of FIG. 12. FIG. 14 is a cross-sectional view taken along line IV-IV′ ofFIG. 12. FIG. 15 is a plan view of a display device according to asecond example embodiment.

With reference to the examples of FIGS. 12 to 14, in the secondembodiment, a lower protective member LP may be disposed on an entirelower surface of a plastic substrate PI, and an upper protective memberUP may be disposed on an upper surface of the plastic substrate PI.Unlike the first embodiment, the lower protective member LP and theupper protective member UP may each have a size larger than the plasticsubstrate PI. Thus, the lower protective member LP and the upperprotective member UP may completely cover the plastic substrate PI sothat the sides of the plastic substrate PI may not be exposed to theoutside, except for the side of the plastic substrate PI on which a padportion PD may be formed.

For example, the pad portion PD may be disposed on the upper surface ofthe plastic substrate PI, and chip-on-films COF may be attached to thepad portion PD. The upper protective member UP may not be attached to aportion of the pad portion PD to which the chip-on-films COF areattached. Thus, the upper protective member UP may be disposed on theentire upper surface of the plastic substrate PI, except for a portionof the pad portion PD. Because the upper protective member UP may havethe size larger than the plastic substrate PI as described above, theupper protective member UP may further protrude to the outside of thesides of the plastic substrate PI, except for the side on which the padportion PD may be formed. For example, as shown in FIG. 12, the upperprotective member UP may protrude further than the upper side, the leftside, and the right side of the plastic substrate PI. In addition, asshown in the examples of FIGS. 12 to 14, the lower protective member LPmay have a size larger than the plastic substrate PI as described above,but may be configured such that one side of the lower protective memberLP may coincide with the lower side of the plastic substrate PI on whichthe pad portion PD may be formed. Thus, the lower protective member LPmay protrude further than the remaining sides of the plastic substratePI, except for the side of the plastic substrate PI on which the padportion PD may be formed.

In the second embodiment, the upper protective member UP may cover bothedges of the plastic substrate PI in the formation area of the padportion PD, and may protrude further than the sides of the pad portionPD. As shown in the example of FIG. 12, the plurality of chip-on-filmsCOF may be attached to the pad portion PD, and edges of the plasticsubstrate PI may be positioned outside the left side and the right sideof the pad portion PD, on which the chip-on-film COF may not beattached. The upper protective member UP may include third protrusionsPP3 protruding to the pad portion PD. The third protrusions PP3 may bedisposed to overlap the edges of the plastic substrate PI. Thus, theupper protective member UP may be disposed on the entire upper surfaceof the plastic substrate PI, except for a portion to which thechip-on-films COF may be attached.

The lower protective member LP may cover both edges of the plasticsubstrate PI in the formation area of the pad portion PD, and mayprotrude further than the sides of the pad portion PD. The lowerprotective member LP may include fifth protrusions PP5 protruding to thepad portion PD. The fifth protrusions PP5 may be disposed to overlap theedges of the plastic substrate PI. Thus, the lower protective member LPmay cover the entire lower surface of the plastic substrate PI, and mayprotrudes from all the sides of the plastic substrate PI, except for aportion to which the chip-on-films COF may be attached.

The upper protective member UP and the lower protective member LPprotruding to the outside of the plastic substrate PI may be attached toeach other using an adhesive layer, and the plastic substrate PI may besealed, except for a portion of the pad portion PD. Further, the thirdprotrusions PP3 of the upper protective member UP and the fifthprotrusions PP5 of the lower protective member LP may be attached toeach other. The upper protective member UP and the lower protectivemember LP protruding to the outside of the plastic substrate PI mayprotrude by a particular length. For example, as shown in the FIG. 13example, lengths “d” of the upper protective member UP and the lowerprotective member LP protruding from the side of the plastic substratePI may be equal to or greater than, e.g., 200 μm. Hence, an adhesivestrength of the upper protective member UP and the lower protectivemember LP can increase, and the plastic substrate PI can be protectedfrom an external impact. The upper protective member UP and the lowerprotective member LP according to the embodiment may be disposed at bothedges of the plastic substrate PI, even in the area in which the padportion PD may be formed. Hence, even when the impact is applied to theedges of the plastic substrate PI, the upper protective member UP andthe lower protective member LP according to the embodiment can preventthe plastic substrate PI from being torn out in the formation area ofthe pad portion PD.

As described above, the upper protective member UP and the lowerprotective member LP may completely cover the plastic substrate PI sothat most of the plastic substrate PI is not exposed to the outside,except for the formation area of the pad portion PD. Therefore, theupper protective member UP and the lower protective member LP canprevent the plastic substrate PI from being damaged by the externalimpact. For example, in the related art, when the side of the plasticsubstrate PI is most vulnerable to an impact and generates cracks, theimpact may be propagated to elements inside the plastic substrate PI,causing damage of the display device. Thus, embodiments may cover thesides of the plastic substrate PI using the upper protective member UPand the lower protective member LP, thereby preventing damage of theplastic substrate PI.

As shown in the FIG. 15 example, as another example of the secondembodiment, the upper protective member UP and the lower protectivemember LP may each have a size greater than the plastic substrate PI,and may be disposed to protrude to the outside of at least one side ofthe plastic substrate PI. For example, the upper protective member UPand the lower protective member LP may be disposed to cover portionsbetween both edges of the plastic substrate PI and the chip-on-films COFin the formation area of the pad portion PD.

For example, the upper protective member UP may include thirdprotrusions PP3 covering both edges at the side of the plastic substratePI on which the pad portion PD is disposed, and fourth protrusions PP4covering the plastic substrate PI between the chip-on-films COF. Forexample, the fourth protrusions PP4 may extend and protrude between thechip-on-films COF, and may be disposed to protrude to the outside of oneside of the plastic substrate PI. Further, the lower protective memberLP may include fifth protrusions PP5 covering both edges at the side ofthe plastic substrate PI on which the pad portion PD is disposed, andsixth protrusions PP6 covering the plastic substrate PI between thechip-on-films COF. For example, the sixth protrusions PP6 may extend andprotrude between the chip-on-films COF, and may be disposed to protrudeto the outside of one side of the plastic substrate PI.

Accordingly, the upper protective member UP and the lower protectivemember LP may seal the plastic substrate PI so that the sides of theplastic substrate PI may not be exposed to the outside throughout theplastic substrate PI, except for a portion to which the chip-on-filmsCOF may be attached. Hence, even when the impact is applied to the edgeof the plastic substrate PI, the upper protective member UP and thelower protective member LP can prevent the plastic substrate PIpositioned at the pad portion PD or the edge of the plastic substrate PIfrom being torn out.

As described above, the display device according to the secondembodiment may form the lower protective member LP having a larger sizethan the entire lower surface of the plastic substrate PI, and may formthe upper protective member UP having a larger size than the entireupper surface of the plastic substrate PI, except for a portion to whichthe chip-on-films COF may be attached. Hence, the display deviceaccording to the second embodiment can prevent the plastic substrate PIfrom being damaged by the impact applied to the side of the plasticsubstrate PI, and can prevent the damage and the defective driving ofthe display device.

FIG. 16 is an image illustrating a display device according to anexample embodiment used in an experiment. FIG. 17 is an imageillustrating an experiment when an impact is applied to a display deviceaccording to an example embodiment. FIG. 18 is an image illustrating anexperiment after an impact is applied to a display device according toan example embodiment.

With reference to FIG. 16, in an experiment, protective members wererespectively attached to an upper surface and a lower surface of aplastic substrate of a display device formed according to an exampleembodiment, on which an organic light-emitting diode was formed. In thisinstance, an upper protective member and a lower protective member wereattached to the plastic substrate to protrude from the side of theplastic substrate by about 200 μm, and were attached to each other. Forreference, the distance from one side of the PI substrate to the tabbonding portion is 30 mm.

As shown in FIG. 17, in an experiment, an impact was applied to theplastic substrate formed according to an example embodiment by bendingan edge of the plastic substrate about twenty (20) times by hand. Asshown in FIG. 18, even when the impact was applied to the plasticsubstrate, the damage, such as a crack, was not found at the edge of theplastic substrate formed according to an example embodiment.

As described above, the display device according to an embodiment mayinclude the protective members, which may be respectively disposed onthe upper surface and the lower surface of the plastic substrate tocover the edge of the pad portion, thereby preventing the plasticsubstrate from being damaged by the impact applied to the side of theplastic substrate. Thus, the display device according to an embodimentcan prevent the damage and the defective driving of the display device.

It will be apparent to those skilled in the art that variousmodifications and variations may be made in the present disclosurewithout departing from the technical idea or scope of the disclosure.Thus, it may be intended that embodiments of the present disclosurecover the modifications and variations of the disclosure provided theycome within the scope of the appended claims and their equivalents.

What is claimed is:
 1. A display device, comprising: a plastic substrate comprising: a display portion comprising organic light emitting diodes; and a pad portion comprising chip-on-films; a lower protective member attached to an entire lower surface of the plastic substrate; and an upper protective member attached to an upper surface of the plastic substrate, the upper protective member covering at least the display portion and both edges of the pad portion.
 2. The display device of claim 1, wherein at least one side of the upper protective member ends coincidentally with at least one side of the plastic substrate.
 3. The display device of claim 1, wherein the upper protective member comprises first protrusions covering both edges of the pad portion.
 4. The display device of claim 3, wherein the upper protective member comprises second protrusions extended between the chip-on-films.
 5. The display device of claim 1, wherein at least one side of the upper protective member and at least one side of the lower protective member protrude to the outside of at least one side of the plastic substrate.
 6. The display device of claim 5, wherein the upper protective member and the lower protective member protruding to the outside of at least one side of the plastic substrate are attached to each other.
 7. The display device of claim 5, wherein the upper protective member comprises third protrusions covering both edges of the pad portion.
 8. The display device of claim 7, wherein the upper protective member comprises fourth protrusions extended between the chip-on-films.
 9. The display device of claim 5, wherein the lower protective member comprises fifth protrusions covering both edges of the pad portion.
 10. The display device of claim 9, wherein the lower protective member comprises sixth protrusions extended between the chip-on-films.
 11. The display device of claim 1, further comprising a resin layer covering the chip-on-films on the pad portion and the pad portion.
 12. A method of manufacturing a display device, comprising: providing a plastic substrate comprising: providing a display portion comprising organic light emitting diodes; providing a pad portion; attaching chip-on-films to the pad portion; attaching a lower protective member to an entire lower surface of the plastic substrate; and attaching an upper protective member to an upper surface of the plastic substrate, the upper protective member covering at least the display portion and both edges of the pad portion.
 13. The method of claim 12, wherein at least one side of the upper protective member ends coincidentally with at least one side of the plastic substrate.
 14. The method of claim 12, wherein the attaching the upper protective member comprises providing first protrusions covering both edges of the pad portion.
 15. The method of claim 14, wherein the attaching the upper protective member comprises providing second protrusions extended between the chip-on-films.
 16. The method of claim 12, wherein at least one side of the upper protective member and at least one side of the lower protective member protrude to the outside of at least one side of the plastic substrate.
 17. The method of claim 16, wherein the upper protective member and the lower protective member protruding to the outside of at least one side of the plastic substrate are attached to each other.
 18. The method of claim 16, wherein the attaching the upper protective member comprises providing third protrusions covering both edges of the pad portion.
 19. The method of claim 18, wherein the attaching the upper protective member comprises providing fourth protrusions extended between the chip-on-films.
 20. The method of claim 16, wherein the attaching the lower protective member comprises providing fifth protrusions covering both edges of the pad portion.
 21. The method of claim 20, wherein the attaching the lower protective member comprises providing sixth protrusions extended between the chip-on-films.
 22. The method of claim 12, further comprising covering the chip-on-films on the pad portion and the pad portion with a resin layer. 